TH-3 Microwave Radio System: Microwave Generator

The microwave generator serves as a low-noise, frequency stable source of beat oscillator power for use in the microwave transmitters and receivers of the TH-3 system. 1 It supplies 140 milliwatts of output power, and can be equipped to supply any one of thirty-two different frequencies in the 5875.2- to 6334.8-MHz frequency range.* A stable crystal-controlled oscillator operates at frequencies between 122.4 and 131.975 MHz. Three tandem transistor frequency doublers are used to multiply the oscillator frequency to 1000 MHz. f The doubler circuits utilize the collector-to-base varactor capacitance of the transistor to enhance the frequency doubling. This results in frequency doubling and power gain simultaneously. A varactor diode sextupler multiplier circuit follows the last transistor doubler to produce the required 6-GHz output power. I I . DESIGN OBJECTIVES The microwave generator was designed to meet the objectives listed below over the normal station air-conditioned temperature range of * This equipment is manufactured by the Western Electric Company for Bell Svstem use onlv. t In this paper 125, 250, 500. 1000. and 6000 MHz are used to denote any frequency between 122.4 and 131.975 MHz and its second, fourth, eighth, and fortyeighth multiple, respectively. 2205